Rescuers sifting through the twisted wreckage of countless towns ravaged by Wednesday's historic tornado outbreak continue to uncover bodies today, and the death toll has swollen to over 300 this morning, and may be as high as 319. Hardest hit was Alabama, with at least 213 dead. Tennessee, Mississippi, Georgia, Arkansas, and Virginia are each reporting 11 - 34 deaths. NOAA's Storm Prediction Center logged 211 preliminary reports of tornadoes between 8am EDT Wednesday and 8am Thursday, and 346 reports for the full 4-day period of the outbreak, from April 25 - April 28. Twenty-two of these tornadoes were killer tornadoes; deaths occurred in six states. Damage surveys will take another week to complete, but preliminary surveys indicate that at least one of the tornadoes was an EF-5--the Smithville, Mississippi tornado, which hit at 3:44pm EDT on Wednesday. That tornado killed 13 people and destroyed 166 buildings, and reportedly sucked fire hydrants out of the ground. Some well-built modern 2-story homes that were bolted to their foundations were completely destroyed, leaving only the foundation. This type of damage is characteristic of an EF-5 tornado with 205 mph winds. The Smithville tornado is the first EF-5 tornado in Mississippi since the Candlestick Park tornado of March 3, 1966. Three other tornadoes from Wednesday's outbreak have been given preliminary EF-4 ratings, with winds of 166 - 200 mph. These include the Phil Campbell, AL tornado (26 deaths), the Ringgold, GA tornado (7 deaths), the Tanner, GA tornado (11 deaths), and the Apison, Tennessee tornado (13 deaths, and possibly the same tornado that hit Ringgold.) The violent tornado that ravaged Tuscaloosa and Birmingham, Alabama, killing at least 46 people and injuring 600, has not yet been given an official rating. I expect this tornado will be rated an EF-4 (possibly an EF-5.) This tornado is likely to be the most expensive tornado of all-time, and damage from the April 25 - 28 outbreak is likely rank as the most expensive tornado outbreak in history. The current record is the $3.5 billion price tag, in 2005 dollars, of the April 3 - 4, 1974 Super Outbreak . According wunderground's weather historian, Christopher C. Burt in his post The World's Deadliest Tornadoes, the death toll of 319 makes the April 25 - 28, 2011 tornado outbreak the fourth deadliest tornado outbreak in U.S. history, and the deadliest since 1936. It is the deadliest of the past 50 years, surpassing the April 3 - 4, 1974 Super Outbreak (315 killed) and the 1965 Palm Sunday tornado outbreak (256 killed.)

Figure 1. Still frame from an animation showing the height and extent of the rain columns associated with the thunderstorms that spawned Wednesday's tornadoes. This data, taken from NASA's TRMM satellite, showed that some of these violent storms reached incredible heights of almost 10.6 miles (17 km.) Image credit: NASA/SSAI, Hal Pierce

The 4-day total of preliminary tornado reports of 346 from this outbreak is close to the 323 preliminary tornado reports logged during the massive April 14 - 16 tornado outbreak. That outbreak has 155 confirmed tornadoes so far, making it the largest April tornado outbreak on record, and 3rd largest in history. The numbers from this week's outbreak may be even higher, giving April 2011 the 3rd and 4th largest tornado outbreaks in history, and the deadliest outbreak in 75 years. According to a list of tornado outbreaks maintained by Wikipedia, only two other tornado outbreaks have had as many as 150 twisters--the May 2004 outbreak (385), and the May 2003 outbreak (401).

Figure 2. Storm chaser video from Reed Timmer and tornadovideos.net of four tornadoes that hit Alabama and Mississippi on Wednesday.

Figure 3. Storm chaser video of the tornado that moved through Philadelphia, Mississippi on Wednesday.

Unprecedented flooding predicted on Ohio and Mississippi RiversThis week's storm system, in combination with heavy rains earlier this month, have pushed the Ohio River and Mississippi River to near-record levels near their confluence. The Ohio River at Cairo, Illinois is expected to crest at 60.5 feet on May 1. This would exceed 100-year flood stage, and be the highest flood in history, besting the 59.5' mark of 1937. Heavy rains of 10 - 15 inches have inundated the region over the past week. Additional rains of 1 - 3 inches are expected over the next five days.

Record 100+ year flood expected on Mississippi RiverSnow melt from this winter's record snow pack across the Upper Mississippi River has formed a pulse of flood waters that is moving downstream. When this floodwater pulse moves south of Cairo, Illinois over the next two weeks, it will join with the record water flow coming out of the Ohio River, and create the highest flood heights ever recorded on the Mississippi, according to the latest forecasts from the National Weather Service. Along a 400-mile stretch of the Mississippi, from Cairo to Natchez, Mississippi the Mississippi is expected to experience the highest flood heights since records began 100 or more years ago, at 5 of the 10 gauges on the river along this stretch. The records are predicted to begin to fall on May 3 at New Madrid, and progress downstream to Natchez by May 20. Areas that are not protected by levees can expect extensive damage from the flooding, and it is possible that the Army Corps of Engineers will have to intentionally dynamite levees at Birds Point and New Madrid, Missouri to protect the town of Cairo from flooding. One unofficial estimate I saw on the Army Corps of Engineers web site put the cost of intentionally breaching the levees at Birds Point and New Madrid at $100 million dollars, due to damage to the croplands and structures in the flooded area. No levee has failed on the Lower Mississippi south of the Ohio River junction since 1950, and the Army Corp of Engineers has designed the levee system to contain a 500-year flood. This means that the Mississippi River flood of 2011--which will be somewhere between a 100-year and 200-year flood between Cairo and Natchez--is not likely to be a multi-billion-dollar disaster like the 1993 flood on the Upper Mississippi, where many levees failed.

The Mississippi River at New Madrid, MO, about 40 miles downstream of the confluence of the Mississippi and Ohio Rivers, is currently at 44.9', the 2nd highest flood in history. The river is predicted to crest on Tuesday very near the all-time record height of 48 feet. The NWS warns that at this height, "Large amounts of property damage can be expected. Evacuation of many homes and businesses becomes necessary." Previous record heights at this location:

The timing of the floods crests will depend upon a complex mix a factors, including how much rain falls over the next month, the possible influence of southerly winds holding up the floodwater pulses, the potential opening of flood control structures and reduction of flows from flood control reservoirs, and potential levee failures. The Mississippi River is expected to crest at 17 feet at New Orleans on May 22, three feet below the top of the levees. This would likely require opening of the Bonnet Carre Spillway 28 miles upstream from New Orleans, to relieve pressure on the city's levees. Opening the spillway drains 250,000 cubic feet per second of flow into Lake Pontchartrain.

Helping out tornado victimsFor those who want to lend a helping hand to those impacted by the widespread destruction this month's severe weather has brought, stop by the portlight.org blog.

@ 520. Nea.If you re-read my comment, you'll see the refinement refers to "subjective assessment" not to the scale itself. I still believe you are splitting hairs. No one in Bridge Creek, OK whose home was wiped clean off the face of Earth would likely give you the time of day if you tried to tell them their tornado wasn't equal to an F5 on the enhanced scale.

It's possible there were more tornadoes in the 1974 Super Outbreak that weren't accounted for, all at the lower end of the Fujita-Pearson scale. I compared the category distributions of severalhigh-count outbreaks between 1992 and 2008, and came up with the following averages:

Just curious, Neap. Where did those numbers come from? Several? Not all of them?

Is June 22 an early start? The 1974 Atlantic Hurricane season also contained 4 sub-tropical storms. June 24 to June 25, July 16 to July 19, August 12 to August 15 and October 4 to October 8. Tropical Depression One developed in the BOC on June 22 and dissipated June 26 above the Catoche Tongue. The last Storm was a relatively late one, Tropical Depression Seventeen, formed November 10 and dissipated November 12.ATL 1974.

Quoting Barefootontherocks:@508. Nea.From one of the links bl posted at 490.When the committee met to develop the Enhanced Fujita Scale (see original document) one point was made very clear: it must continue to support and maintain the original tornado database.; In other word, there must be some conformity to that of the F-Scale that is listed in the database.

When these scales were "blended" it was done in a way that intentionally preserved previous plain old "F" designations.

You state many tornadoes were likely overestimated.Maybe some were underestimated. New scale does not eliminate subjective assessment. Just refines it. 'fraid your argument doesn't hold water with me.

Also, there were 7 (E)F5s in 1974 super outbreak, not 6. See link at comment 481 - official SPC list.

Well, my math was hardly scientifically perfect. But given the strength distributions of every other major outbreak of the past several decades, it's far more likely that a number of the 1974 SO storms were mistakenly placed into a category higher than they should have been rather than vice versa. One would have to admit that it would require an extremely anomalous outbreak indeed to produce 300% more F3s, 1300% more F4s, and 1400% more F5s than the what the long-term averages would dictate.

Even Dr. Fujita himself recognized the limitations and possibilities for errors in his original scale--especially at the higher end of it--and he was working towards a better method when he retired (and even afterward). You're right in stating the the Enhanced Scale doesn't remove subjectivity--but its designers did more than simply refine it.

Is June 22 an early start? The 1974 Atlantic Hurricane season also contained 4 sub-tropical storms. June 24 to June 25, July 16 to July 19, August 12 to August 15 and October 4 to October 8. Tropical Depression One developed in the BOC on June 22 and dissipated June 26 above the Catoche Tongue. The last Storm was a relatively late one, Tropical Depression Seventeen, formed November 10 and dissipated November 12.ATL 1974.

EPAC 1974

WPAC 1974.

When compared to some years it is an early start.So if we look at this in the big picture it seems that if history repeats it's self this season will start early and end late??

Quoting washingtonian115: And!! the season got off to an early start.Boy this is interesting!!!!!.Yes yes yes!!.I'm gonna look into this more.The U.S was also affected by a major hurricane.It was western Louisiana.The same place that in all the analog years was affeted.Man this is awesome!! information/history I'm getting.Also their were storms that affected the east coast.Another place that's at risk this year.The western/southern section of Florida was affected that year.Which just some happens to be at higher risk this year.1974 has become a close analog.With almost same weather patterns.

Is June 22 an early start? The 1974 Atlantic Hurricane season also contained 4 sub-tropical storms. June 24 to June 25, July 16 to July 19, August 12 to August 15 and October 4 to October 8. Tropical Depression One developed in the BOC on June 22 and dissipated June 26 above the Catoche Tongue. The last Storm was a relatively late one, Tropical Depression Seventeen, formed November 10 and dissipated November 12.ATL 1974.

@508. Nea.From one of the links bl posted at 490,When the committee met to develop the Enhanced Fujita Scale (see original document) one point was made very clear: it must continue to support and maintain the original tornado database.; In other word, there must be some conformity to that of the F-Scale that is listed in the database.

When these scales were "blended" it was done in a way that intentionally preserved previous plain old "F" designations.

You state many tornadoes were likely overestimated.Maybe some were underestimated. New scale does not eliminate subjective assessment. Just refines it. 'fraid your argument doesn't hold water with me.

Also, there were 7 (E)F5s in 1974 super outbreak, not 6. See link at comment 481 - official SPC list.

Quoting washingtonian115:And!! the season got off to an early start.Boy this is interesting!!!!!.Yes yes yes!!.I'm gonna look into this more.The U.S was also affected by a major hurricane.It was western Louisiana.The same place that in all the analog years was affeted.Man this is awesome!! information/history I'm getting.Also their were storms that affected the east coast.Another place that's at risk this year.The western/southern section of Florida was affected that year.Which just some happens to be at higher risk this year.1974 has become a close analog.With almost same weather patterns.

Quoting washingtonian115:Mmmm now that you bring that up very interesting.Ahhhh now I'm looking at the hurricane season.Very interesting.Mmm I might have to add 1974 to my analog years.Sooo if history is repeating it's self this should be an active hurricane seaqson.I also noticed that in that year two storms formed in June.And the U.S was affected.Ah yes very interesting indeed...

And!! the season got off to an early start.Boy this is interesting!!!!!.Yes yes yes!!.I'm gonna look into this more.The U.S was also affected by a major hurricane.It was western Louisiana.The same place that in all the analog years was affeted.Man this is awesome!! information/history I'm getting.Also their were storms that affected the east coast.Another place that's at risk this year.The western/southern section of Florida was affected that year.Which just some happens to be at higher risk this year.1974 has become a close analog.With almost same weather patterns.

Severe Thunderstorm Warning for Faulkner, Lonoke, Pulaski, Saline and White County in AR until 10:15pm CDT. #arwx 6 minutes ago Tornado Warning for Camp, Cass, Morris, Titus and Upshur County in TX until 9:45pm CDT. #txwx 33 minutes ago Severe Thunderstorm Warning for Faulkner, Garland, Perry, Pulaski and Saline County in AR until 9:30pm CDT. #arwx 52 minutes ago Severe Thunderstorm Warning for Livingston, Lyon, and Marshall County in KY until 9:00pm CDT. #kywx about an hour ago Severe Thunderstorm Warning for Fulton, Izard, Sharp and Stone County in AR until 9:15pm CDT. #arwx about an hour ago Tornado Warning for Camp, Morris, Titus and Upshur County in TX until 9:15pm CDT. #txwx about an hour ago Severe Thunderstorm Warning for Clay and Greene County in AR until 9:00pm CDT. #arwx about an hour ago Severe Thunderstorm Warning for Garland, Montgomery, Perry and Saline County in AR until 8:45pm CDT. #arwx about an hour ago

Quoting TomTaylor:That super outbreak of 1974 likely had many more than 148 tornadoes in 24 hrs but reporting 40 years ago is nothing like it is today. Simply judging by the amount of F5s vs EF5s from that outbreak to this one, it is likely that had all the tornadoes been reported, this present outbreak would not have surpassed the number of tornadoes in the1974 outbreak.

It's possible there were more tornadoes in the 1974 Super Outbreak that weren't accounted for, all at the lower end of the Fujita-Pearson scale. I compared the category distributions of several high-count outbreaks between 1992 and 2008, and came up with the following averages:

If the distribution for the 1974 Super Outbreak is normalized with the average distribution I found, and based on having accurate numbers for only F4s and F5s, it would have produced the following approximate counts:

However--this whole exercise might be moot, and in fact almost certainly is. The Fujita-Pearson scale was based on highly subjective and error-prone damage descriptions, and didn't take into account differences in construction methods, building types, etc. (in fact, one of the reasons the Enhanced Fujita Scale was developed). Because of that, many tornadoes were likely overestimated, with some F2s being called F3s, some F3s being called F4s, and some F4s being called F5s. If that is taken into consideration, this week's outbreak may actually have seen more storms than did the 1974 one. It wouldn't be surprising if the actual counts for the 1974 outbreak were very similar to this week's. I'm sure there were some 10-yard-wide, 25-yard-long F0s uncounted in 1974.

At any rate, at the middle- and high-ends of the scale, there's little reason to think there were any more unreported storms in 1974 than there were this week; an F4 or F5 is hard to miss, especially in the crowded eastern U.S.

Mmmm now that you bring that up very interesting.Ahhhh now I'm looking at the hurricane season.Very interesting.Mmm I might have to add 1974 to my analog years.Sooo if history is repeating it's self this should be an active hurricane seaqson.I also noticed that in that year two storms formed in June.And the U.S was affected.Ah yes very interesting indeed...

RECENT TRENDS PER LIT WSR-88D INDICATED THE STORM OVER GARLAND COUNTY AR WAS BECOMING SUPERCELLULAR /INFLOW NOTCH AND LOW LEVEL ROTATION/ AND TRACKING ESE AT 25 KT. 00Z LIT SOUNDING SHOWED THECAP HAD WEAKENED SINCE 12Z WITH A RATHER MOIST BOUNDARY LAYER AS CURRENT SURFACE OBSERVATIONS ACROSS CENTRAL/SRN AR INDICATED AN INCREASE IN SURFACE DEWPOINTS TO THE UPPER 60S. THIS IS CONTRIBUTING TO A MODERATELY UNSTABLE AIR MASS. MEANWHILE...STRENGTHENING SWLY LLJ TO 40 KT PER LIT WSR-88D VWP DATA IS RESULTING IN INCREASING LOW LEVEL SHEAR /SFC-1 KM SRH 420 M2 PER S2/. THIS COMBINED WITH AFOREMENTIONED THERMODYNAMICS AND OBJECTIVE ANALYSES SHOWING EFFECTIVE INFLOW IS SURFACE BASED PROVIDES CONCERN THAT THIS STORM COULD PRODUCE A TORNADO.

OTHER STORMS DEVELOPING AND/OR MOVING INTO CENTRAL AR WILL NEED TO BE MONITORED FOR SIMILAR TRENDS AND THREAT.

AFTER A REVIEW OF THE DAMAGE PHOTOS TAKEN DURING THURSDAY/S GROUND SURVEY AND CONSULTATION WITH NATIONAL EXPERTS...THE NATIONAL WEATHER SERVICE IN MEMPHIS HAS UPGRADED THE SMITHVILLE TORNADO RATING TO EF-5 DAMAGE. THIS IS THE HIGHEST RATING FOR TORNADO DAMAGE AND THE FIRST EF-5 OR F-5 IN MISSISSIPPI SINCE THE CANDLESTICK PARK TORNADO NEAR JACKSON ON MARCH 3RD 1966.

* COUNTY/COUNTIES: MONROE

* LOCATION/TIME OF EVENT: SMITHVILLE AT 344 PM EDT ON APRIL 27 2011

* BEGINNING POINT: 34.0517, -88.4236

* ENDING POINT: 34.0731, -88.3814

* RATING: EF-5

* ESTIMATED PEAK WIND: 205 MPH

* PATH LENGTH: 2.82 MILES

* MAXIMUM WIDTH: 1/2 MILE

* FATALITIES: 14

* INJURIES: 40

* SUMMARY OF DAMAGES: 18 HOMES DESTROYED...2 BUSINESSES /POST OFFICE AND POLICE STATION/DESTROYED... 8 HOMES WITH MAJOR DAMAGE...7 BUSINESSES WITH MAJOR DAMAGE...44 HOMES WITH MINOR DAMAGE...AND WATER SYSTEM DESTROYED. MOST TREES EITHER SNAPPED OR TWISTED AND DEBARKED. MOST THE HOMES DESTROYED WERE WELL BUILT...TWO STORIES...LESS THAN TEN YEARS OLD AND BOLTED DOWN TO THEIR FOUNDATIONS. A 1965 CHEVY PICKUP TRUCK PARKED IN FRONT OF ONE OF THE DESTROYED HOMES HAS NOT BEEN FOUND. ALL APPLIANCES AND PLUMBING FIXTURES IN THE MOST EXTREME DAMAGE PATH SHREDDED OR MISSING.

The Fujita-Pearson Scale or The Fujita Scale?The scale was original created in 1971 by Dr. Fujita as a way of determining the strength of tornadoes from the damage that they caused. Like many of the contributions of Dr. Fujita, it was not widely accepted when first published.

Dr. Fujita and Dr. Pearson two years later published a paper that added in factors related to the width and length of the tornado path, and called the scale the Fujita-Pearson Scale. It was this work that caused the scale to gain acceptance.

The Storm Prediction Center now uses the greatly improved Fujita Scale to determine tornado strength from the damage that the tornado causes after the tornado.

Yet when a spotter or anyone else from the field makes a judgment about the size of a tornado without damage data, but on the width and length of the tornado path, they are making that judgment based on the size of the tornado on the ground, which is the Pearson method.

BTW, that pronunciation of Cairo sure illustrates the shift in American English at the dialectal level... obviously when this town was formed, enough pple who lived in the area pronounced it Kay-roh [as opposed to Kaiy-roh] for that to become the established name.

Whoa, Mr. Tilley... way to show u r not doing your job as a representative!!! This flood plan has been floated for weeks... long enough to go get some court decision about it, if I remember correctly, but you haven't gone down to see your constituents about a plan that's likely to devastate their farming possibilities for the year????? I love the "me first" attitude, plus the "the other guys stink anyhow" attitude at the end....

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